1. Technical Field
The invention generally relates to a power supply apparatus, and more particularly, to a power supply apparatus having an external over voltage compensation and/or a voltage-difference detection for performing feedback compensation.
2. Related Art
In applications of several high-end electronic products (such as a server or an industrial computer), two power suppliers with the same specification and having negative feedback control functionality are usually coupled in parallel, so as to simultaneously provide the required electric power to the electronic product in operation. When one of the power suppliers is not functioning due to over voltage, the other power supplier is utilized to continue supplying the electric power to the electronic product.
In practice, when one of the power suppliers is over voltage, or the feedbacks of both power suppliers have a deviation, due to the negative feedback control, a duty cycle of the control signal generated by the voltage feedback controller inside the said one will be correspondingly decreased. However, when the duty cycle of the control signal is decreased to a limit, the power supplier may no longer be functioning. At this time, due to the load of the other power supplier is increased drastically, there is likely an oversized voltage drop occurring in the electric power provided by such power supplier. If the electric power suddenly drops below the minimum power specification of the electronic product, it may cause the electronic product switch off without any warning, or cause the system of the electronic product very unstable.